Currently in supermarkets multideck coolers are used to display a variety of fresh, pre-packed food products. These products are normally highly perishable and will go off very rapidly, especially if the maximum allowable temperature is exceeded. In many countries there is legislation that products which have been stored at temperatures above the maximum allowed temperature, these products may either not be sold anymore or the sell-by date must be reduced. The latter is often not easy as the sell-by date is pre-printed on the package and cannot be changed easily. Under normal circumstances, the multideck coolers used to display such products ensure that that temperature is ensured. However, when the cooler is not packed properly (too much products are inside the cooler) the airflow is disturbed and the heat generated by the lamps under the shelves will drive up the shelf temperature beyond the maximum allowable temperature. This problem makes that supermarkets are hesitant to put lighting under shelves as they might legally be held liable when foods products have been gone off as a result of exceeding the maximum temperature or if there is a claim from, for example, the Food and Drug Administration (US), Foods Standards Agency (UK) or ‘Voedsel en warenauthoriteit’ (Netherlands).
US 2007087614 A2 describes a control system for an illuminated display case, the display case including a sensor that may be used as a switch or as a controller to adjust the power being provided to the light sources of the display case. Further, an implementation of a control scheme is described wherein the voltage to the light sources is shut off when the sensor detects that the temperature inside the display case exceeds a predetermined temperature. When the temperature inside the display case returns to acceptable levels, the light sources are provided with power.
With conventional illuminated displays there is a risk for temperature over-shoot as ambient conditions change frequently. Therefore, there is a need for an improved illumination control.